Solve Cryptography Exercises: Rabbin & RSA Protocols

I have stuck at these two exercises in the book "Introduction to Cryptography" by Johannes Buchmann. In the first exercise, we are using the Rabbin protocol with the parameters p=31, q=51, and B=15. We want to transmit the message M=20 and determine the encrypted message C and the decrypted messages the recipient will receive. In the second exercise, we are working in RSA with Alice's public key (n,e)=(667,3). We have m1=26, m2=46, and Alice's signature of m1. We need to find the signature of m2 without factoring 667 or finding the private key. We can give Alice a message x that is different from m2 and
  • #1
kopros
3
0
Hi I have stuck at these two exercises ...



1)

Suppose we use the Rabbin protocol and we have chosen p=31,q=51 and B=15. If we want to transmit the message M=20 which will be the encrypted message C?? Also what are the messages the recipient will receive decrypting C ??



2)

Suppose we work in RSA and Alice has the public key (n,e)=(667,3). Suppose m1=26, m2=46, and the signature of Alice in m1 is sig(m1). We want to find sig(m2). We have the right to give her a message x, x different from m2 and she will sign it. We can't use the factoring of 667 neither can we find the d from e=3. What message should we give her?

thnx alot
 
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  • #2
kpros,

was this assigned as a homework problem in a class?

just curious.

DJ
 
  • #3
Hi,
no I am just trying to solve them from a book I study these days..
 
  • #4
kopros said:
Hi,
no I am just trying to solve them from a book I study these days..

Kopros,

What's the name of the book?

DJ
 
  • #5
Introduction to Cryptography by Johannes Buchmann
 
  • #6
I'll see if I have a copy. DJ
 

Related to Solve Cryptography Exercises: Rabbin & RSA Protocols

1. What is cryptography?

Cryptography is the practice and study of techniques for secure communication in the presence of third parties. It involves encoding and decoding information to prevent unauthorized access or tampering.

2. What is the Rabbin cryptosystem?

The Rabbin cryptosystem is a public-key cryptosystem invented by Ron Rivest, Adi Shamir, and Leonard Adleman in 1977. It is one of the first and most widely-used public-key encryption methods, and is based on the difficulty of factoring large integers.

3. How does the Rabbin cryptosystem work?

The Rabbin cryptosystem uses two large prime numbers, p and q, to generate a public key and a private key. The public key is used for encryption, while the private key is used for decryption. The security of the system relies on the difficulty of factoring the product of p and q.

4. What is the RSA protocol?

The RSA protocol is a widely-used public-key cryptosystem based on the difficulty of factoring large integers. It was invented by Ron Rivest, Adi Shamir, and Leonard Adleman in 1977 and is used for secure communication and digital signatures.

5. How does the RSA protocol work?

The RSA protocol uses a public key and a private key to encrypt and decrypt messages. The public key is used for encryption, while the private key is used for decryption. The security of the system relies on the difficulty of factoring the product of two large prime numbers, which are used to generate the keys. The RSA protocol is also used for digital signatures, where the private key is used to sign a message and the public key is used to verify the signature.

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